GB2198585A - Magnetic circuit breaker - Google Patents

Abstract

A circuit breaker includes a vacuum or gas-filled sealed casing 1, a stationary contact 2, a movable contact 4, a linkage 100 connected to the movable contact 4, a tension spring 7 for activating the linkage 100, a latch 8 for normally hindering the linkage 100 from movement resulting from the tension spring 7, a manual set and reset mechanism 200 for moving the movable contact 4 to electrically connect with and disconnect from the stationary contact 2, and an automatic indicating device 300 drivable by the linkage 100 to indicate the state of over-load or short-circuit. When the circuit is converted to the state of over-load or short-circuit, the linkage 100 will be released from the latch 8 by an electomagnet 10, 11 a bimetal so that the movable contact 4 will be pulled by the tension spring 7 away from the stationary contact 2 to open the circuit. Two pairs of mutually attractable magnetic members M1 and 61, M2 and 18 are respectively used to transfer motions between the linkage 100 and the manual set, reset mechanism 200 as well as between the linkage and automatic indicating device. Magnetic member M1 is movable by a rotary handle 15 to attract or allow pivoting of the member 61. On overload, member 18 moves to attract member M2 and bring a trip sign into a window 24. <IMAGE>

Description

MAGNETIC VACUUM CIRCUIT BREAKER The invention relates to a magnetic circuit breaker with a simple structure which transfers motion to open the circuit, by means of a linkage, under over-load or short-circuit.

In conventional electrical switches, especially those used in power circuits, the contacts are exposed to air, whether the contacts are of the knife or magnetic type. These kinds of switches are unsuitable for use in dusty, moist, easily explosive or combustible environments. Several different types of switches for preventing explosions have been developed, such as oil switches, safety switches, and so forth.

However, due to the complex structures of these switches, they are unpractical from a manufacturing standpoint. Accordingly, I disclosed an automatic magnetic switch in the application Ser. No. 967,712 filed on December 8, 1978 which issued as U.S. Pat. No.

4,288,767. The automatic magnetic switch is simpler than the conventional switches in structure. However, the circuit is switched off under over-load or shortcircuit by the complicated motion from a protection means 7 through a magnetic control means 10 to a magnetic contacting plate means 8, as shown in Fig. 1.

Thus, the structure of the automatic magnetic switch may again desire simplification.

An object of the invention is to provide a simple circuit breaker which automatically switches off a power circuit when the power circuit is over loaded.

Another object of the invention is to provide a simple circuit breaker with a manual reset switch whereby once the power circuit is switched off under over-load, one can manually reset the switch to close the circuit, and whereby once the load is under accidental emergency, one can instantly, manually switch off the circuit.

Still another object of the invention is to provide a simple circuit breaker with an automatic indicating device whereby the TRIP state of the circuit under over-load or short-circuit is indicated.

According to the invention, a circuit breaker includes a casing; a contact device sealed in the casing, including a stationary contact and movable contact normally contacting the stationary contact; a linkage connected to the movable contact in the casing; a first lower magnetic member, pivotally mounted in the casing, connected to and disposed above the linkage, rotatable between a first upper and lower dead points to activate the linkage and hence the movable contact to connect with and disconnect from the stationary contact, positioned normally at the first upper dead point; a first tension spring interconnecting the first lower magnetic member and the linkage for biasing the linkage and hence the movable contact away from the stationary contact; an electrically driven stop device, connected to the linkage for normally hindering the linkage from movement under the tension force of the first tension spring, responsive to the state of overload or short-circuit by releasing the linkage to be biased by the first tension spring to move the movable contact away from the stationary contact; a manual reset switch, including a sub-casing fixed on the upper wall of the casing, an actuator member movable between an ON and OFF positions in the sub-casing, and a first upper magnetic member drivable by the actuator member to move, in the sub-casing, toward or away from the first lower magnetic member for generating or releasing the magnetic attractive force between the first upper and lower magnetic members to form an ON or OFF state, the release of the magnetic attractive force between the first upper and lower magnetic members causing the first lower magnetic member to rotate to the first lower dead point so as to activate the linkage to move the movable contact away from the stationary contact, the magnetic attractive force between the first upper and lower magnetic member being larger than the tension force of the first tension spring; and an automatic indicating device for being driven by the linkage to indicate the state of over-load or short-circuit under over-load or short-circuit; whereby, when the circuit is converted to the state of over-load or short circuit, the linkage is released from the stop device to move, then, due to the linking-up motion of the linkage resulting from the tension force of the first tension spring, the movable contact will move away from the stationary contact to open the circuit, simultaneously, the over-load or short-circuit state will be indicated by the automatic indicating device; subsequently, the manual reset switch is reset to restore the magnetic switch to a normally closed position.

An embodiment of the invention will now be described by way of example, with reference to the accompanying drawings in which: Fig. 1 is a vertical sectional view of a magnetic switch according to prior art; Fig. 2 is a vertical sectional view of a circuit breaker according to the invention in a normally closesd position; Fig. 3 is a schematic view showing the linking-up motion of the linkage of the circuit breaker of Fig. 2 under over-load or short-circuit; Fig. 4 is a schematic view showing the partial analysis of the linking-up motion of the linkage of Fig. 2; Fig. 5 is a schematic view showing the linking-up motion of the linkage of the circuit breaker of Fig. 2 when a manual reset switch is switched off; Fig. 6 is a top view showing the manual reset switch of the circuit breaker of Fig. 2; and Fig. 7 is a horizontal section taken substantially on the line 7-7 of Fig. 2 and illustrating the relation of the push rod and , the longitudinal crank arm of the forked rotary member in broken lines.

Referring to Fig. 2, a circuit breaker according to the invention includes a sealed casing 1 including a generally U-shaped stationary central frame 101 fixed therein; a contact device, mounted in the casing 1, including a stationary contact 2 electrically connected to the left segment 3 of an electrical wire screwed to the casing 1, and a movable contact 4 electrically connected to the right segment 5 of the electrical wire and normally contacting the stationary contact 2; a linkage 100 connected to the movable contact 4; a slidable rotary member 6, including a first magnetic block 61 carried at the upper end thereof, and a longitudinal slide slot S1 provided on the left end portion of the slidable rotary member 6 for being pivotally mounted on the stationary frame 101 above the linkage 100, rotatable between a first upper dead point, as shown in the solid line of Fig. 5, and a first lower dead point, as shown in the broken line of Fig. 5, to activate the linkage and hence the movable contact 4 to connect with and disconnect from the stationary contact 2, positioned normally at the first upper dead point; a first tension spring 7 interconnecting the slidable rotary member 6 and the linkage 100 for biasing the linkage 100 and hence the movable contact 4 away from the stationary contact 2; a stop device, connected to the linkage 100 for normally hindering the linkage 100 from movement under the tension force of the first tension spring 7; and a maunal reset switch 200, mounted on the upper wall of the casing 1; and an automatic indicating device 300 drivable by the linkage 100 to indicate the state of over-load or short-circuit under over-load or shortcircuit.

It should be noted that a vacuum is normally maintained within the casing 1 for the purpose of duration. Alternatively, the casing 1 may be filled with an inert gas.

The stop device includes a first L-shaped crank C1, pivotally mounted on the stationary frame 101 by a first stationary pivot P1, including a left crank arm with a raised stopper 8 on the left crank arm for normally blocking a portion of the linkage 100 to hinder the linkage 100 from movement under the tension force of the first tension spring 7, and a right crank arm with a pin 9 at the free end of the right crank arm; an axial torsion spring (not shown) mounted on the first stationary pivot P1 of the first L-shaped crank C1 for biasing the first L-shaped crank C1 to rotate clockwise; an electromagnet, including a core 10, and a coil 11 surrounding the core 10 and electrically connected to the right segment 5 of the electrical wire; an inverted V-shaped armature 12, rotatably disposed between the electromagnet and the first Lshaped crank C1, including a right arm normally spaced from the core 10 , and a left arm normally abutting on the pin 9 to, permit the stopper 8 to block the portion of the linkage 100, and a second tension spring 13, connected to the left arm of the armature 12 for biasing the right arm of the armature 12 away from the core. The magnetic attractive force between the right arm of the armature 12 and the electromagnet is larger than the tension force of the second tension spring 13 under over-load or short-circuit.

The manual reset switch 200 includes a sub-casing 14 fixed on the upper wall of the casing 1, a rotary knob 15 with an axle 16 in the sub-casing 14 and rotatable between an ON and OFF position, and a first permanent magnet M1 secured to the axle 16 for rotating horizontally. The magnetic pole of the first permanent M1 is movable toward or away from the first magnetic block 61 via a first bridging magnet B1 for generating or releasing the magnetic attractive force between the first permanent magnet M1 and the first magnetic block 61 to form an ON or OFF state. The magnetic attractive force between the first permanent magnet M1 and the first magnetic block 61 is larger than the tension force of the first tension spring 7.

The release of the magnetic attractive force between the first permanent magnet M1 and the first magnetic block 61 permits the slidable rotary member 6 to rotate clockwise to the first lower dead point so as to activate the linkage 100 to move the movable contact 4 away from the stationary contact 2, as shown in the broken line of Fig. 5.

The automatic indicating device 300 includes a push rod 17 integral with the axle 16 and having a generally barb-shaped free end 171 with a rounded end surface (see Fig. 7); a second magnetic block 18 rotatably connected to the linkage 100 for falling to a second lower dead point due to gravity, as shown in the solid line of Fig. 3 when the circuit is in a normal state or as shown in Fig. 5 when the maunal reset switch 200 is switched off, and for being driven by the linkage 100 to rotate to a second upper dead point, as shown in the broken line of Fig. 3 when the circuit is converted to the state of over-load or shortcircuit; and a forked rotary member 19, rotatably longitudinally disposed between the push rod 17 and the second magnetic block 18, rotatable between an upper and lower position.The push rod 17 is movable between an ON-position as shown in the solid line of Fig. 7 and an OFF-position as shown in the broken line of Fig. 7.

The forked rotary member 19 includes a horizontal crank arm 191, including a forked free end 20, a second permanent magnet M2 secured to the lower branch 21 of the forked free end 20 and attractable by the second magnetic block 18 to rotate the forked rotary member 19 clockwise when the seond magnetic block 18 moves to the second upper dead point under over-load or short-circuit, and two indicating characters indicated on the upper branch 22 of the forked free end 20, one charater being "TRIP" directed by a broken arrow Al, and the other character being "NORMAL" directed by a solid arrow A2, as shown in Fig. 6, the two arrows Al and A2 being spaced from each other at a predetermined distance which is dependent on the relation between the upper and lower positions of the forked rotary member 19;; a longitudinal crank arm 192, capable of being pushed by the push rod 17 to rotate the forked rotary member 19 anticlockwise after the second permanent magnet M2 has been attracted by the second magnetic block 18 via a second bridging magnet B2 due to overload or short-circuit and when the manual reset switch 200 is switched on to move the push rod 17 to register with said longitudinal crank arm 192 of the forked rotary member 19 (see Fig. 7); a third tension spring 23 for biasing the second permanent magnet M2 away from the second magnetic block 18 to rotate the forked rotary member 19 anticlockwise, the tension force of the third tension spring 23 being smaller than the magnetic attractive force between the second permanennt magnet M2 and the second magnetic block 18; and a glass indicating window 24 normally aligned with the solid arrow A2 in a manner well known to those skilled in the art.

Referring to Fig. 2, the linkage 100 includes in turn from the left to the right: (1) a second L-shaped crank C2, pivotally mounted on the stationary frame 101 at the left end portion of the linkage 100 by a second stationary pivot P2, including a left crank arm connected to the slidable rotary member 6 by the first tension spring 7 and connecting the movable contact 4 to the left end of the right segment 5 of the electrical wire by an electrically conductive portion 25 on the left crank arm of the second L-shaped crank C2, and a right crank arm;; (2) a four-bar sub-linkage, consisting of a first coupler L1 at the left upper portion, a second coupler L2 at the left lower portion, a first single-arm crank C3 pivotally mounted on the stationary frame 101 by a third stationary pivot P3 at the right lower portion, and a rotatable frame at the right upper portion. It is connected to a pivot of the slidable rotary member 6 by a third coupler L3 at a movable pivot R1 between the second coupler L2 and the first single-arm crank C3.

Additionally, it is connected to a second movable pivot R2 of the right crank arm of the second L-shaped crank C2 by a fourth coupler L4 at the movable pivot R3 between the first coupler L1 and the second coupler L2; (3) an inverted T-shaped crank C3', pivotally mounted on the stationary frame 101 by the third stationary pivot P3, including a left crank arm forming a rotatable frame of the four-bar sub-likage, an intermediate crank arm, and a right crank arm; (4) a third L-shaped crank C4, disposed at the right upper end portion of the linkage 100, including a horizontal slide slot S2 for being pivotally mounted on the stationary frame 101 by a fourth stationary pivot P4, including an upper crank arm carrying the second magnetic block 18, and a lower crank arm connected to the intermediate crank arm of the inverted T-shaped crank C3' by a fifth coupler L5; and (5) a second single-arm crank C5, pivotally mounted on the stationary frame 101 at the right upper end portion of the linkage 100 by a fifth stationary pivot P5, capable of being obstructed, so as to fail to rotate clockwise, by the stopper 8 at the free end of the second single-arm crank C5, connected to the right crank arm of the inverted T-shaped crank C3' by a sixth coupler L6 at an intermediate portion of the second single-arm crank C5.

The linking-up motion of the linkage 100 under over-load is shown in Fig. 3. Once the circuit is over loaded, the right arm of the armature 12 is attracted by the electromagnet to rotate clockwise so that the left arm of the armature 12 pushs the first Lshaped crank C1 to rotate anticlockwise, thereby causing the stopper 8 to move away from the free end of the second single-arm crank C5 so as to permit the first tension spring 7 to activate the linkage 100.

In the linking-up motion of linkage 100 under over-load, referring to Fig. 4, the third coupler L3 is pivoted to the slidable rotary member 6. Thus, the first movable pivot R1 between the third coupler L3 and the first single-arm crank C3 is fixed at a position as shown in Fig. 4 due to the fact that two interconnecting cranks are incapable of rotating.

When the free end of the second single-arm crank C5 is released, as shown in Fig. 3, the first tension spring 7 will pull the movable contact 4 away from the stationary contact 2 to rotate the second L-shaped crank C2 clockwise so as to rotate the second movable pivot R2 to the right, then, the fourth coupler L4 and hence the first coupler L1 push the inverted T-shaped crank C3' to rotate clockwise, thereby rotating the third L-shaped crank C4 anticlockwise through the fifth coupler L5 to move the second magnetic block 18 to the second upper dead point, to attract the second permanent magnet M2, and simultaneously rotating the second single-arm crank C5 clockwise through the sixth coupler L6.

When the second permanent magnet M2 is attracted by the second magnetic block 18 to rotate, the forked rotary member 19 rotates clockwise to the lower position where the longitudinal crank arm 192 of the forked rotary member 19 moves to the position as shown in broken line of Fig. 7, the broken arrow Al indicated on the horizontal crank arm 191 of the forked rotary member 19 is brought into registry with the indicating window 24, i.e. it is visible from the indicating window 24.

Subsequently, when the circuit is restored to normal condition from over-load state, the right arm of the armature 12 is pulled by the second tension spring 13 away from the electromagnet and the first L-shaped crank C1 is biased by the torsion spring (not shown) to rotate clockwise beyond the position of Fig. 2, it is therefore necessary to reset. Firstly, the manual reset switch 200 is switched off so that the magnetic pole of the first permanent magnet M1 is moved away from registry with the first magnetic block 61 to permit the first magnetic block 61 to move to the first lower dead point. Secondly, the manual reset switch 200 is switched on so that the first magnetic block 61 is attracted by the first permanent magnet M1 to return to the first upper dead point.Simultaneously, referring to Fig. 7, the push rod 17 pushs the longitudinal crank arm 192 of the forked rotary member 19 to rotate the forked rotary member 19 anticlockwise by the assistance of the third tension spring 23, thereby moving the second magnetic block 18 to the second lower dead point so as to restore completely the normal position shown in Fig. 2, and thereby simultaneously rotating the forked rotary member 19 to the upper position where the solid arrow A2 is visible from the indicating window 24.

Referring to Fig. 5, when an emergency is encountered by the circuit, the manual reset switch 200 can be instantly switched off so as to open the circuit. When the manual reset switch 200 is switched off, the slidable rotary member 6 will move to the first lower dead point, as described above. Since the stopper 8 blocks the free end of the second single-arm crank C5, the inverted T-shaped crank C3' is incapable of rotation. Thus, the downward movement of the slidable rotary member 6 and hence the third coupler L3 causes the first single-arm crank C3 to rotate anticlockwise so that the second L-shaped crank C2 is rotated clockwise to move the movable contact 4 away from the stationary contact 2.

It should be understood that the upper wall of the casing 1 is preferably provided with the bridging magnets B1 and B2 respectively disposed between the first permanent magnet M1 and the first magnetic block 61 as well as the second permanent magnet M2 and the second magnetic block 18 in order to concentrate the magnetic flux to thus enhance the attractive force therebetween.

Additionally, the longitudinal and horizontal slide slots S1 and S2 respectively are used to facilitate smooth movement of the first and second magnetic blocks 61, 18 at the very inception of starting.

Alternatively, the stop device may be replaced by other arrangement, such as a b-metal device or other electromagnetic relays.

With the invention thus explained, it is apparent that various modifications and variations can be made without departing from the scope of the invention. It is therefore intended that the invention be limited as indicated in the appended claims.

Claims (10)

CLAIMS:

1. A circuit breaker comprising: a casing; a contact device, sealed in said casing, including a stationary contact and a movable contact normally contacting said stationary contact; a linkage connected to said movable contact in said casing; a first lower magnetic member, pivotally mounted in said casing, connected to and disposed above said linkage, rotatable between a first upper dead point and a first lower dead point to activate said linkage and hence said movable contact to connect with and disconnect from said stationary contact, normally positioned at the first upper dead point; a first tension spring interconecting said first lower magnetic member and said linkage for biasing said linkage and hence said movable contact away from said stationary contact;; an electrically driven stop device, connected to said linkage for normally hindering said linkage from movement under the tension force of said first tension spring, responsive to the state of over-load or shortcircuit by releasing said linkage to be biased by said first tension spring to move said movable contact away from said satationary contact;; a manual reset switch, including a sub-casing fixed on the upper wall of said casing, an actuator member movable between an ON and OFF position in said sub-casing, and a first upper magnetic member drivable by said actuator member to move in said sub-casing toward or away from said first lower magnetic member for generating or releasing the magnetic attractive force between said first upper and lower magnetic members to close or open the circuit, the release of the magnetic attractive force between said first upper and lower magnetic members causing said first lower magnetic member to rotate to the first lower dead point so as to activate said linkage to move said movable contact away from said stationary contact, the magnetic attractive force between said first upper and lower magnetic members being larger than the tension force of said first tension spring; an automatic indicating device drivable by said linkage to indicate the state of over-load or shortcircuit under over-load or short-circuit; whereby, when the circuit is converted to the state of over-load or short-circuit, said linkage is released from said stop device, then, due to the linking-up motion of said linkage resulting from the tension force of said first tension spring, said movable contact will move away from said stationary contact to open the circuit, simultaneously, the overload or short-circuit state will be indicated by said automatic indicating device; subsequently, said manual reset switch is reset to restore the magnetic switch to a normally closed position.

2. A circuit breaker as claimed in Claim 1, wherein said electrically driven stop device comprises: a first L-shaped crank, including a left crank arm with a raised stopper on said left crank arm capable of blocking a portion of said linkage for hindering said linkage from movement under the tension force of said first tension spring, and a right crank arm with a pin at the free end of said right crank arm; a torsion spring mounted on said first L-shaped crank for biasing said first L-shaped crank to block said portion of said linkage; an electromagnet, including a core, and a coil surrounding said core and electrically connected to an electrical wire;; an inverted V-shaped armature, rotatably disposed between said electromagnet and said first L-shaped crank, including a right arm normally spaced from said core of said electromagnet, and a left arm normally abutting on said pin of said first L-shaped crank to permit said stopper to block said portion of said linkage, whereby, when said right arm of said armature is attracted by said electomagnet under over-load or short-circuit, said left arm of said armature will push said pin of said first L-shaped crank to rotate said first L-shaped crank so as to move said stopper away from said portion of said linkage, thereby activating said linkage to move said movable contact away from said stationary contact; and a second tension spring for biasing said left arm of said armature away from said electromagnet, the magnetic attractive force between said right arm of said armature and said electromagnet under over-load or short-circuit being larger than the tension force of said second tension spring;

3. A circuit breaker as claimed in Claim 1, wherein said automatic indicating device comprises:: a push rod, mounted in said sub-casing, secured to and drivable by said actuator member of said manual reset switch to rotate, including a rounded free end rotatable horizontally between an ON and OFF position; a second lower magnetic member, mounted in said casing, rotatably connected to said linkage for falling to a second lower dead point due to gravity when the circuit is in a normal state or when said manual reset switch is switched off, and for being driven by said linkage to rotate to a second upper dead point when the circuit is converted to the state of over-load or short-circuit; and a rotary member, mounted in said sub-casing, rotatably longitudinally disposed between said push rod and said second lower magnetic member, rotatable between an upper and lower positions, including: a horizontal crank arm, inclcuding a twopronged free end, a second upper magnetic member secured to one branch of said free end and attractable by said second lower magnetic member to rotate said rotary member clockwise when said second lower magnetic member moves to the second upper dead point under overload or short-circuit, and two indicating characters indicated on the other branch of said two-pronged free end, one character being "NORMAL" and the other character being "TRIP" indicated above said character "NORMAL", said two characters being spaced from each other at a predetermined distance which is dependent on the relation between the upper and lower positions of said rotary member; a longitudinal crank arm, capable of being pushed by said rounded free end of said push rod to rotate said rotary member anticlockwise when said manual reset switch is reset after over-load or shortcircuit; a third tension spring for pulling said second upper magnetic member away from said second lower magnetic member to rotate said rotary member anticlockwise, the tension force of said third tension spring being smaller than the magnetic attractive force between said second upper and lower magnetic members; a transparent indicating window normally aligned with said character "NORMAL".;; whereby, when the circuit is converted to overload or short-circuit state, said character "TRIP" is visible from said indicating window.

4. A circuit breaker. as claimed in Claim 1, wherein said linkage includes: a second L-shaped crank, mounted at the left end portion of said linkage, including a left crank arm connected to said first lower magnetic member by said first tension spring, and a right crank arm; a four-bar sub-linkage, connected to said right crank arm of said second L-shaped crank by a coupler, and connected to said first lower magnetic member by a coupler; an inverted T-shaped crank, including a left crank arm forming a rotatable frame-of said four-bar sub-linkage, an intermediate crank arm, and a right crank arm; a third L-shaped crank, mounted at the right end portion of said linkage, including an upper crank arm carrying said second lower magnetic member, and a lower crank arm connected to said intermediate crank arm of said inverted T-shaped crank by a coupler; and a single-arm crank, mounted at the right end portion of said linkage, connected to said right crank arm of said inverted T-shaped crank by a coupler at an intermediate portion of said single-arm crank, having a free end normally blocked by sawi stopper of said stop device so as to fail to rotate under the tension force of said first tension spring.

5. A circuit breaker as claimed in Claim 1, wherein said actuator member of said manual reset switch is a rotary knob.

6. A circuit breaker as claimed in Claim 1, wherein vacuum is maintained within said casing.

7. A circuit breaker as claimed in Claim 1, wherein said casing is filled with an inert gays.

8. A circuit breaker as claimed in Claim 1, wherein casing includes a first bridging magnet disposed on said casing between said first upper and lower magnetic members so as to concentrate t magnetic flux to enhance the magnetic attractive force therebetween.

9. A circuit breaker as claimed in Claim 1, wherein said casing inciudes a second bridging magnet disposed on said casing between said second upper and lower magnetic members so as to concentrate the magnetic flur to enhance the magnetic attractive force therebetween.

10. A circuit breaker as claimed in claim 1 and substantially as described with reference to Figures 2 to 7 of the accompanying drawings.